This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: RFC: Handling of libgcc symbols in SH shared libraries
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Joern Rennecke <joern dot rennecke at superh dot com>
- Cc: gcc at gcc dot gnu dot org, kkojima at rr dot iij4u dot or dot jp (Kaz Kojima), amylaar at spamcop dot net
- Date: 10 Aug 2004 16:57:25 -0300
- Subject: Re: RFC: Handling of libgcc symbols in SH shared libraries
- Organization: Red Hat Global Engineering Services Compiler Team
- References: <200408021838.i72IcCL03743@chloe.uk.w2k.superh.com>
On Aug 2, 2004, Joern Rennecke <joern.rennecke@superh.com> wrote:
> For now, for SFUNC_GOT, I always make function_symbol generate
> @GOT addressing, although for most functions that is not strictly
> necessary: they could use @PLT addressing, as long as it is guaranteed
> that the symbol is resolved at load time (or earlier with pre-linking).
But why would you want @PLT addressing instead of @GOT addressing? It
would have a performance impact, since the @PLT code would just do the
load from GOT and jump to the loaded address (with a possible pipeline
stall on the memory load), whereas if you load the address from the
GOT and call it directly you can schedule better. Sure, it's one
additional instruction per call, so it may have negative code size and
thus cache effects. How badly would you like to get rid of it?
--
Alexandre Oliva http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}